The present subject matter relates generally to an outer ear bone anchor. More specifically, the present invention is a bone anchor that may be secured within the outer ear to provide a stable base to which other devices may attach, be stabilized or pass through.
The entirety of the disclosure of the following additional references is hereby incorporated into this disclosure: (1) Plontke S K, Zimmermann R, Zenner H, and Lowenheim. Technical note on microcather implantation for local inner ear drug delivery: surgical technique and safety aspects. Otology and Neurotology. 2006; 27: 912-917. (2) Silverstein H, Thompson J, Rosenburg S I, Brown N, and Light J. Silverstein MicroWick. Otolaryngology Clinics of North America. 2004; 37: 1019-1034, and (3) Thomsen J, Charabi S, and Tos, Mirko. Preliminary results of a new delivery system for gentamicin to the inner ear in patients with Meniere's disease. European Archives of Otolaryngology. 2000; 257: 362-365.
The ear divides anatomically into three sections: external auditory canal (EAC), the middle ear and the inner ear. The EAC consists of the auditory meatus (the opening of the ear), the canal itself, followed by the tympanic membrane (TM), which is the boundary between the EAC and the middle ear. The middle ear is an air-filled cavity within the temporal bone that contains the ear bones, which, from lateral to medial, are the malleus, incus, and stapes. The lateral wall of the middle ear is partially bound by the TM and the medial wall is bounded by the inner ear, which is encased in bone. The inner ear is comprised of the cochlea, which contains cells that detect sound, and the vestibular apparatus, which contains cells that detect motion. Both the cochlea and the vestibular apparatus are a maze of fluid-filled tubes that run through the temporal bone of the skull.
There are situations in which delivery of medication to the inner or middle ear may be advantageous. For example, there may be conditions, such as some forms of hearing loss, that may be positively affected by the use of medication as described in Melki, S. J., Heddon, C. M., Frankel, J. K., Levitt, A. H., Momin, S. R., Alagramam, K. N. and Megerian, C. A. (2010), Pharmacological protection of hearing loss in the mouse model of endolymphatic hydrops, The Laryngoscope, 120: 1637-1645. doi: 10.1002/lary.21018, the entirety of which is incorporated herein by reference. However, current delivery methods are invasive, and, in some instances, may harm the middle and/or inner ear.
Traditional invasive medication delivery methods, as detailed by Thomsen et al. 2000 and Plontke et al. 2006, include implanting a medication delivery pump and catheter under the skin and within the temporal bone of the patient, so that the delicate middle and inner ear structures are not harmed by transmission of external forces through the device that are the result of normal daily activity. This often requires extensive and intricate drilling of the temporal bone, which can result in damage to delicate cochlear and vestibular structures, middle ear structures, the brain, vascular structures and the facial nerve. This procedure also requires general anesthesia and hospital admission, both of which are significant sources of morbidity and mortality. The Silverstein MicroWick (Silverstein et al. 2004) is an alternate method for delivery of medication to the inner ear that involves using a polyacetate wick as a conduit for medications to be delivered to the inner ear via the round window membrane (RWM). The wick itself travels though TM via a pressure equalization tube (PE tube). Placement of this device is temporary and, after placement, the PE tube is meant to be used intermittently in the treatment of sudden sensorineural hearing loss, vertiginous symptoms of Meniere's disease, and diseases that do not necessarily require continuous drug infusion. Aside from the temporary nature of PE tube placement, the wick must be replaced every four weeks in order to prevent adhesion to middle ear mucosa. These and other current methods of medication delivery to the middle and inner ear are invasive, painful, and in some instances, ineffective.
There are disease states of the cochlea and vestibular system that would benefit greatly from continuous infusion of therapeutic agent (including, but not limited to medications, growth factors, nanoparticles, genetic factors), as continuous delivery optimally treats the most distal portions of the cochlea and vestibular structures. The superiority of continuous drug delivery over intermittent delivery in treating the entire hearing and vestibular apparatus has been shown in computer, animal and human models.
In addition to medication delivery, there are other conditions and procedures that involve the placement of materials into the middle or inner ear. In one such example, hearing aids utilizing cochlear implants require the implantation of an electrode array in the inner ear, the electrode is then connected to an associated receiver. In order to prevent damage to the sensitive portions of the middle and inner ear, cochlear implants have been implanted by drilling through the mastoid bone, located behind the ear, rather than being implanted through the ear itself. There are other implantable hearing devices that require drilling into the temporal bone. Use of these devices could be augmented or supplanted by the incorporation of an outer ear bone anchor, as provided herein. The devices that would benefit most include, but are not limited to, bone anchored hearing aids (BAHAs) and middle ear implants. In some iterations, an external receiver resting behind the inner ear could be easily connected and disconnected to/from a wire that sits at the external auditory meatus and more distally attaches to the bone anchor. The configuration from the point of the anchor inward would depend upon the nature of the device. For a BAHA or middle ear implant type device, a vibrating element may emanate from the hardware attached to the anchor and may contact the ossicles, the medial wall of the middle ear, the round window, the oval window or some other portion of the ear. The mechanism of the vibrating element could be piezoelectric, magnetic or electromagnetic. In other iterations, the receiver could be miniaturized and placed entirely within the middle ear with the canal-based anchor serving as the anchor point for the entire device.
As shown, there are numerous situations in which access to the middle and inner ear involves invasive drilling through the bone structure surrounding the ear or other invasive or potentially damaging action. Accordingly, there is a need for device and method adapted to provide access to the inner and middle ear that is less invasive and has a lower potential for harm to the patient.